A power management circuit operable to reduce energy loss is provided. The power management circuit is configured to provide a time-variant voltage(s) to a power amplifier(s) for amplifying an analog signal(s). To achieve best possible operating efficiency at the power amplifier(s), the time-variant voltage(s) needs to rise and fall frequently and quickly in accordance with power fluctuations of the analog signal(s). The power management circuit stores an electrical potential energy (e.g., capacitive energy) when the time-variant voltage(s) increases and discharges the electrical potential energy when the time-variant voltage(s) decreases. In embodiments disclosed herein, the power management circuit is configured to harvest a portion of the discharged electrical potential energy to thereby charge a battery. By harvesting the discharged electrical potential energy, it is possible to prolong battery life concurrent to supporting fast and frequent voltage changes.